Spool for typewriter ribbon



April 1959 P. REGENTROP ET'AL 2,881,894

I SPOOL FOR TYPEWRITER RIBBQN Filed Sept. 1'7, 1956 2 Sheets-Sheet 1 70 77 4 N Q l v April 1959 P. REGENTROP ET AL 2,881,894

SPOOL FOR TYPEWRITER RIBBON Filed Sept. 17, 1956 2 Sheets-Sheet 2 United States Patent 2,881,894 SPOOL FOR TYPEWRITER RIBBON Paul Regentrop and Walter Fastenrath, Wuppertal- Elberfeld, Germany Application September 17, 1956, Serial No. 610,248 Claims priority, application Germany September 19 1955 7 Claims. (Cl. 197-175) This :invention relates to ofiice equipment, and more particularly to spools for typewriter ribbons and the like.

Spools for typewriter and other ofiice machine ribbons usually comprise two circular discs spaced by a cylindrical core on which the ribbon is to be wound. For the purpose of mounting the spool carrier pin of the typewriter or other office machine, a cylindrical guide is provided 1n and coaxial with the core; with metal spools, this guide may be provided, for example, in the form of a small tube inserted in the core. The two discs conform in having three apertures displaced relative to one another by 120 any one of which may be engaged by the driving pin, arranged on the typewriter or other machine, of the ribbon transport mechanism.

It is a primary object of the present invention to provide an improved spool for typewriter ribbons and the like, which is made all in one piece by injection molding in a faultless, uniform manner and at a maximum saving of material.

Other objects, and the manner in which the same are attained, will become apparent as this specification proceeds.

The invention contemplates a spool for typewriter ribbons and the like made from artificial material all in one piece, wherein from the hollow cylinder whereby the spool is inserted on the spool mounting pin, radial slots extend any one of which is susceptible to being engaged by the driving pin of the machine, and where the walls of the said slots are interconnected by transverse walls the outer confines of which define, the same as the outermost wall portions of the slots, a cylinder mantle corresponding to the core of the spool. This arrangement results not only in a faultless, uniform manufacture of the spool by injection molding, but moreover, in a maximum saving of material in the course of such manufacture. For purposes of obtaining a product with superior overall characteristics, it is recommended to use the same wall thickness for all parts of the spool, a wall thickness of from about 0.8 to about 1.0 mm. being preferred, in order to eliminate any danger of stresses existing in the finished spool.

In the drawing accompanying this application and forming part thereof, one embodiment of the invention is illustrated by way of example.

In the drawing,

Fig. 1 shows a top view of a spool according to the invention;

Fig. 2 is a section taken along line H-II in Fig. 1;

Fig. 3 is a section taken along line HI-III in Fig. 1;

Fig. 4 is a section taken along line IV-IV in Fig. 1;

Fig. 5 is a horizontal section through the spool illustrated in Fig. 1, taken along line V-V in Fig. 6, and

Figs. 6 and 7 are side views, from the right and the left, respectively, of the spool shown in Fig. 1.

Referring now to the several figures of the drawing wherein like elements are denoted by identical reference numerals, the circular lateral discs are identified as 8 and 9 throughout. The center aperture designed 2,881,894 Patented Apr. 14, 1959 ice - parts 13 are disposed in a common cylinder mantle the axis of which coincides with the axes of the spool and the hollow cylinder 10, respectively. The walls 12 of the slots, on the outside, are interconnected by transverse walls 14; in the embodiment of the invention illustrated in the drawing, four such transverse walls 14 are provided. These transverse walls extend from the hollow cylinder 10 outwardly over a distance such that their outer edges are disposed in the cylinder mantle defined by the outer confines of portions 13. This cylinder mantle corresponds to the core of the spool on which the ribbon is to be wound.

The outer confines of the transverse walls 14 are sulficiently close to one another that together with the outer surfaces of portions 13, they form a cylindrical core which in spite of the narrow interstices in its surface, insures a smooth support for the ribbon to be wound thereon.

The arrangement of the spool according to the above outline of the basic features of the invention renders possible a manufacture of the spool all in one piece by injection molding and at a maximum saving of material, particularly if the wall thickness of all parts is made approximately equal, preferably in a range of from about 0.8 to about 1 mm., to the exclusion of thicker portions. While material dilferences in the wall thicknesses of the various portions might result, on cooling of the injection molded article, in stresses which in turn might lend to cracks or fissures in the finished spool, the observation of a more or less uniform wall thickness throughout all parts of the spool eliminates any such danger.

For the purpose of insertion of the conventional pointed sheet metal strip, for securing the ribbon on the spool, one of the walls 13 for one of the slots 11 (in the embodiment illustrated in the drawing, the slot 11a) is provided with a slit 15 extending in the direction of the axis of the spool, which slit, by means of connecting walls 16, extends to the hollow cylinder 10. This slit is so dimensioned that there remains, in the slot 11a, suflicient space for the entry therein, from either side, of a driving pin of the machine. In order that the pointed sheet metal strip, together with the end of the ribbon attached thereto, can be forced into the mantle of the cylindrical core of the spool so nothing projects therefrom, the portion 13 provided with the slit 15, on one side of the slit, has a recess 17 which is extended by corresponding marginal recesses 18 in the adjacent transverse walls 14. These recesses are best seen in Fig. 5.

The window in the core of the spool, a traditional feature of spools for typewriter ribbons, is replaced by corresponding cut portions 19 which are provided on the two central transverse walls 14, on the side of the spool opposite the slit 15 (cf. Figs. 1 and 5).

We wish it to be understood that we do not desire to be limited to the details of construction, design and operation of the invention as outlined, for purposes of illus tration only, in the foregoing specification, as numerous modifications falling within the scope of the appended claims and involving no sacrifice of the advantages of the invention nor any departure from the spirit thereof, may occur to a person skilled in the art.

We claim:

1. Spool for typewriter ribbons and the like made all in one piece of artificial material, comprising in combination, two discs, a hollow cylinder centrally arranged between said discs and extending substantially over the entire distance between said discs, a plurality of slots radially extending from the hollow interior of said cylinder and axially extending over substantially the entire length of said cylinder, Walls on the side of said slots, transverse walls interconnecting said side walls, walls at the outer ends of said slots, theoutside of said end walls and the outer edges of said transverse walls being disposed to define a cylinder mantle corresponding to the core of the spool.

2. Spool for typewriter ribbons and the like according to claim 1, wherein the end wall of one of the slots is provided with a slit extending'in the direction of the spool axis, and connecting walls extend said slit to the hollow cylinder.

3. Spool for typewriter ribbons and the like according to claim 2, wherein the end wall provided with .the axially extending slit, on one side, has a recess, and wherein the two adjacent, centrally disposed transverse walls have their outer edges recessedto extend vsaidrecess.

4. Spool for typewriter ribbons andtlie like according to claim 3, wherein on the side of the spool opposite saidslit, the centrally disposed transverse walls include cut-01f portions, to replace the conventional spool window.

5. Spool for typewriter ribbons and the like according to claim 4, wherein all parts have approximately the same wall thickness whereby to avoidstresses in the finished spool.

'6. Spool for typewriter ribbonsandthelike according to claim 5, wherein the wall thickness common toallparts ranges from 0.8 to 1.0 mm,

7. Spool for typewriter ribbons and the like according to claim 1, wherein the plurality of-slotsare evenly angularly displaced, in star-fashion.

References Cited in the fileof this patent UNITED STATES PATENTS 

